Invalidate subsequence caching & empty paint phases if clips changed.

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintPropertyTreeBuilder.h"
 
 #include "core/dom/DOMNodeIds.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
@@ skipping 792 matching lines @@
   }
 }
 
 void PaintPropertyTreeBuilder::updateOutOfFlowContext(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
   if (object.isLayoutBlock())
     context.paintOffsetForFloat = context.current.paintOffset;
 
   if (object.canContainAbsolutePositionObjects()) {
+    LOG(ERROR) << "Updated abspos stuff: " << object.debugName();
     context.absolutePosition = context.current;
     context.containerForAbsolutePosition = &object;
   }
 
   if (object.isLayoutView()) {
     if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
       const auto* initialFixedTransform = context.fixedPosition.transform;
       const auto* initialFixedScroll = context.fixedPosition.scroll;
 
       context.fixedPosition = context.current;
@@ skipping 154 matching lines @@
   updateOverflowClip(object, context);
   updatePerspective(object, context);
   updateSvgLocalToBorderBoxTransform(object, context);
   updateScrollAndScrollTranslation(object, context);
   updateOutOfFlowContext(object, context);
 
   context.forceSubtreeUpdate |= object.subtreeNeedsPaintPropertyUpdate();
 }
 
 }  // namespace blink